140 



SCIENCE 



[N. S. Vol. XXVII. No. 682 



The book begins with a well-balanced esti- 

 mate of the relative value of observational 

 and experimental work; it maintains that 

 experiment is the only method by which zool- 

 ogy may be placed upon the same footing with 

 chemistry and physics; it points out the uses 

 and abuses of scientific hypotheses and the 

 necessity of verifying these by experiment; 

 and it concludes that the goal of experimental 

 work is, in the words of Loeb, the control of 

 natural phenomena. 



The scope of experimental zoology is so 

 great that it can not be treated as a whole 

 vpithin a volume of ordinary size. The author 

 has therefore omitted from consideration two 

 important fields of study, viz., experimental 

 embryology and the experimental study of 

 regeneration, both of which he has dealt with 

 in other books. The present volume is mainly 

 devoted to those aspects of experimental 

 zoology which have not hitherto received ade- 

 quate treatment in book form. 



The principal topics discussed fall under 

 the following six headings: (1) Experimental 

 Study of Evolution, (2) Experimental Study 

 of Growth, (3) Experimental Studies in 

 Grafting, (4) Experimental Studies of the 

 Influence of the Environment on the Life- 

 cycle, (5) Experimental Studies of the De- 

 termination of Sex, (6) Experimental Study 

 of the Secondary Sexual Characters. 



Under the first heading are included a large 

 number of topics such as the influence of ex- 

 ternal conditions in causing changes in the 

 structure of animals, the inherited effects of 

 changes due to environment, the inheritance 

 of acquired characters, experimental hybrid- 

 izing, the behavior of the germ cells in cross 

 fertilization, inbreeding, the influence of 

 selection, and finally the theory of evolution. 

 These topics are dealt with unequally, the 

 first in particular being very brief, while 

 the last is from its nature rather more 

 speculative than experimental in character. 

 There is everywhere, however, a wealth of 

 reference to works on these topics and many 

 valuable and stimulating suggestions. With 

 the chapters on experimental hybridizing I 

 think it may be said that Morgan first strikes 

 his gait in this book. This subject is treated 



at much length and in a thorough and ad- 

 mirable manner. 



The section of the book on experimental 

 studies on evolution forms rather more than 

 half of the whole work. The remaining sec- 

 tions deal with subjects of a more special 

 character. Under the experimental study of 

 growth, the chapters on the external factors 

 that influence growth, and on growth and 

 regeneration are especially worthy of favor- 

 able mention. A single chapter is devoted to 

 experimental studies on grafting, but this 

 chapter is one of the best in the book, and it 

 shows at once the author's intimate and exten- 

 sive acquaintance with this subject. In the 

 chapters on the experimental studies of the 

 influence of the environment on the life-cycle 

 Morgan has brought together results which 

 are probably less familiar to the average zool- 

 ogist than are any other topics dealt with in 

 the book. The literature references in these 

 chapters indicate through what a range of 

 publications, many of them relatively inac- 

 cessible and but little known, the author has 

 labored in preparing this summary. 



The final sections on the determination of 

 sex and on secondary sexual characters deal 

 with some of the most interesting subjects in 

 zoology. The various hypotheses are consid-' 

 ered fairly and judicially and the author's 

 own views are set forth in a form which is 

 clear, if not always convincing, and which is 

 sure to stimulate research. And after all this 

 last is perhaps the greatest service which any 

 book can render. In a work which covers so 

 wide a field it is natural that minor faults 

 should occur, but it would be unjust to sup- 

 pose that it does not also have great merits. 

 Morgan has placed all zoologists under obliga- 

 tion because of this book ; it has been received 

 with the highest commendations abroad, and it 

 is a work of which American zoologists may 

 well be proud. Edwin" G. Conklin 



The Soil-preferences of Certain Alpine and 



Suhalpine Plants. By M. L. Eeenald. 



Contr. from the Gray Herbarium. Ehodora, 



September, 1907. 44 pp. 



It is refreshing to find, in this study of 

 Eemald, a distinct departure from the hack- 



